(1) Field of the Invention
The instant invention relates to a seal of the lip-seal variety for providing a seal between a piston member and piston cylinder of the type generally used in fluid-actuated transmissions.
(2) Description of the Prior Art
Fluid-actuated transmissions generally include one or more fluid-actuated pistons, each disposed within a corresponding cylinder. In order to properly function, a seal is required to maintain pressure within the piston chamber. Elastomeric ring seals have been used for perfecting the seal between the piston and the cylinder. Generally, these seals include a lip extending outwardly therefrom for perfecting the seal.
The design of these prior art seals require an additional means for maintaining the seal in place. This construction requires either additional structural features to be cast as part of the piston for retaining the seal thereon, such as a groove, or other additional fastening members, such as a separate retaining ring for securing the ring in place.
Means for maintaining a seal in place comprising an annular steel ring molded within the seal are well known in the art of making rotating seals. U.S. Pat. No. 2,797,944 to Riesing discloses one example of a seal reinforced by an annular metal ring. The Riesing seal discloses the use of a ring fabricated from metal strip which features serations on one edge to facilitate elastomer flow therearound. Since the ring is formed from steel strip it is prone to handling damage, especially prior to being molded into the seal. If the ring is mishandled, it may be dented or deformed, causing it to be unsuitable for use in a seal. Another example of such a seal is disclosed in U.S. Pat. No. 3,346,265 to Rhoads which discloses the use of a laminated metal reinforcing member made from a plurality of metal strips. The strips are knurled on one side to facilitate elastomer flow between the strips. The laminated construction is durable, but is too expensive for most seal applications.
The instant invention solves the above problems by providing a seal which includes integral means for maintaining the seal on a mounting surface that is inexpensive, simple to manufacture and resistant to handling damage.